Re: [libvirt] [PATCH v2 6/7] domain_lock: Implement metadata locking

On Tue, Aug 14, 2018 at 01:19:42PM +0200, Michal Privoznik wrote: > In order for our drivers to lock resources for metadata change we > need set of new APIs. Fortunately, we don't have to care about > every possible device a domain can have. We care only about those > which can live on a network filesystem and hence can be accessed > by multiple daemons at the same time. These devices are covered > in virDomainLockMetadataLock() and only a small fraction of > those can be hotplugged (covered in the rest of the introduced > APIs). I'm not sure I understand the rationale behind saying we only care about resources on network filesystems. If I have 2 locally running guests, and both have a serial port backed by a physical serial port, eg <serial type="dev"> <source path="/dev/ttyS0"/> <target port="1"/> </serial> we *do* care about locking /dev/ttyS0, as libvirtd isn't doing mutual exclusion checks anywhere else for the /dev/ttyS0 device node. In general I think we need to lock every single file resource that is labelled for a guest, regardless of whether its local or remote.